Breadcrumb trail

NRC titanium foam promises better treatment for scaphoid fractures

February 01, 2012— Ottawa, Ontario

Sheldon Souray — a big NHL defenceman with a booming slapshot — has been injured many times during his career and has twice had surgery to repair fractures to the scaphoid, a thimble-sized bone at the base of the thumb. Such injuries, which usually occur when a person throws out their hands to break a fall, are very common but notoriously difficult to treat.

X-rays frequently fail to detect scaphoid fractures. They’re sometimes misdiagnosed as sprains and they often fail to heal properly — even when the injured limb is placed in a cast or when doctors implant a screw. But an innovative new titanium foam screw — developed by NRC researcher Louis-Philippe Lefebvre and McGill University orthopedic surgeons Paul Martineau and Ed Harvey — may stimulate healing while greatly reducing the pain and discomfort of those who sustain such injuries.

“The scaphoid is a really nasty bone to break,” says Dr. Martineau. “We often see people who think they’ve sprained their thumb and decide to tough it out. Sometimes they’ll go two years and then come to us in horrible pain.”

A top 10 invention

Lefebvre and Dr. Martineau are close to completing bio-mechanical tests on the screw, after which it must undergo tests in animals before being approved for use in humans. But the researchers have already received outside recognition for their work. In its February 2012 issue, the popular magazine Québec Science included the device in its top 10 inventions in the province last year and asked readers to vote for their favourite.

Lefebvre, who is based at NRC’s industrial materials facility in Boucherville, Quebec, has been working with titanium for close to a decade. Titanium is a strong, lightweight, corrosion-resistant metal used in hundreds of products — from drill risers to golf clubs to jet engine components — and Lefebvre has added to this list.

Making titanium foam

He makes titanium foam by blending titanium powder with a polymeric binding powder and foaming agent, pouring the mixture into a mould and then heating the contents. The foaming agent, which acts like baking powder in bread dough or a cake mix, decomposes when heated and releases gases that cause bubbling, which leaves porosity in the titanium screw.

NRC has already licensed its foam technology to several companies, including one that’s using it in veterinarian applications for the treatment of cruciate ligament diseases, a firm that hopes to use it in the manufacture of hip replacement devices, another that is developing dental implants, and a fourth one that use it in the heat exchangers found in computers.

While titanium implants have long been used in orthopedic surgery, “we realized there was interest among orthopedic surgeons in porous titanium that would lead to better bone fixation,” says Lefebvre.

Titanium foam screws and the hardware used to insert them into bone.

Better outcomes for patients

A titanium foam screw, which would be inserted into the centre of the scaphoid bone, has two unusual features that should lead to better
outcomes for patients: first, it has a hollow core that allows surgeons to inject substances, such as growth factor, to stimulate the formation of new bone tissue. Second, new bone tissue can grow within the surface pores of the screw, which means the bone should adhere more firmly to the implant.

Dr. Martineau is confident the titanium foam screw will be approved for use in humans. “If our screw works on the scaphoid, we’ll be able to use larger versions to treat other fractures,” he adds.